Properties of Magnesium Chelatase in Greening Etioplasts: METAL ION SPECIFICITY AND EFFECT OF SUBSTRATE CONCENTRATIONS |
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| Authors: | Fuesler T P Wright L A Castelfranco P A |
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| Affiliation: | Department of Botany, University of California, Davis, California 95616. |
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| Abstract: | Evidence was obtained by means of low temperature spectrofluorimetry and high pressure liquid chromatography for the exclusive chelation of Mg2+ into protoporphyrin IX by a plastid preparation extracted from greening cucumber cotyledons. Under the experimental conditions which were optimized for Mg2+ chelation, Zn2+ chelation was not detected. However, Zn2+ chelation was observed when ATP was omitted and ZnCl2 was added to the incubation mixture. The observed Zn2+ chelation was partially nonenzymic. The requirements for the enzyme, Mg chelatase, are discussed in terms of the regulatory function of this enzyme. |
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